I don't this this fix is correct, I am able to reproduce the crash in a
hyper-v VM and this generates a different KASAN bad free with the repro
case.
If you want to test (and have an environment with an SRIOV interface), you can
toggle SRIOV rapidly with this powershell snippet:
$vmname= 'name of vm'
while (1){
Set-VMNetworkAdapter -VMName $vmname -IovWeight 100
Set-VMNetworkAdapter -VMName $vmname -IovWeight 0
}
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Packages, which is subscribed to linux-azure in Ubuntu.
https://bugs.launchpad.net/bugs/1973758
Title:
Azure: Mellanox VF NIC crashes when removed
Status in linux-azure package in Ubuntu:
Invalid
Status in linux-azure source package in Focal:
In Progress
Bug description:
SRU Justification
[Impact]
The 5.4.0-1075-azure and newer kernels are broken in that the VM can
easily panic when the Mellanox VF NIC is removed and added due to
Azure host servicing events or the below manual "unbind/bind" test
(here the GUID can be different in different VMs):
for i in `seq 1 1000`;
do
cd /sys/bus/vmbus/drivers/hv_pci;
echo abdc2107-402e-4704-8c88-c2b850696c3c > unbind;
echo abdc2107-402e-4704-8c88-c2b850696c3c > bind;
done
A sample panic call-trace is:
[ 107.359954] kernel BUG at
/build/linux-azure-5.4-4I3kFs/linux-azure-5.4-5.4.0/mm/slub.c:4020!
[ 107.363858] invalid opcode: 0000 [#1] SMP NOPTI
[ 107.365870] CPU: 0 PID: 334 Comm: kworker/0:2 Not tainted 5.4.0-1077-azure
#80~18.04.1-Ubuntu
[ 107.369589] Hardware name: Microsoft Corporation Virtual Machine/Virtual
Machine, BIOS 090008 12/07/2018
[ 107.373811] Workqueue: events vmbus_onmessage_work
[ 107.375909] RIP: 0010:kfree+0x1d2/0x240
…
[ 107.413789] Call Trace:
[ 107.414867] kobject_uevent_env+0x1b5/0x7e0
[ 107.416747] kobject_uevent+0xb/0x10
[ 107.418327] device_release_driver_internal+0x191/0x1c0
[ 107.420653] device_release_driver+0x12/0x20
[ 107.422523] bus_remove_device+0xe1/0x150
[ 107.424279] device_del+0x167/0x380
[ 107.425824] device_unregister+0x1a/0x60
[ 107.427536] vmbus_device_unregister+0x27/0x50
[ 107.429528] vmbus_onoffer_rescind+0x1d0/0x1f0
[ 107.431474] vmbus_onmessage+0x2c/0x70
[ 107.433104] vmbus_onmessage_work+0x22/0x30
[ 107.434919] process_one_work+0x209/0x400
[ 107.436661] worker_thread+0x34/0x40
It turns out there is a bug in https://git.launchpad.net/~canonical-
kernel/ubuntu/+source/linux-
azure/+git/bionic/commit/?id=16a3c750a78d8, which misses the second
hunk of the upstream patch
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=877b911a5ba0.
Please apply the below patch to fix the issue:
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3653,7 +3653,7 @@ static int hv_pci_remove(struct hv_device *hdev)
hv_put_dom_num(hbus->bridge->domain_nr);
- free_page((unsigned long)hbus);
+ kfree(hbus);
return ret;
}
BTW, please apply this patch as well (Note: this patch is not really required
as it's only for error handling path, which is usually unlikely):
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=42c3d41832ef4fcf60aaa6f748de01ad99572adf
[Test Case]
Microsoft tested
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